KR100741680B1 - Centrifugal separator - Google Patents

Abstract

In the inclined separator type centrifugal separator, sludge is discharged directly from the lowest water content in the bowl to reduce water content and improve separation efficiency.

In a centrifugal separator containing a screw conveyor rotated at a high speed rotating bowl with a relative speed difference, a discharge path 20 of the dehydrated mass is provided in one end wall 2 of the bowl, and the bowl of the path is provided. The opening 20a into the inner part is formed near the inner circumferential wall of the bowl, and the discharge path has a throttle effect on the discharge of the dehydrated mass, and is formed as a thick deposited layer near the opening.

As a result, the discharge mass from the discharge diameter is only from the portion of the sedimentation layer deposited at one end of the bowl, where the consolidation effect due to the head pressure of centrifugal force acting on the deposit is the highest. It is discharged via diesel.

Description

Centrifugal Separator {CENTRIFUGAL SEPARATOR}

The present invention relates to a centrifugal separator in which sewage sludge, industrial wastewater, and all products for the chemical and food industries are concentrated, dehydrated, and precipitated heavy components are recovered by centrifugal force.

For solid-liquid separation, such as sludge, a decanter centrifugal separator is generally used. As shown in FIG. 7, this separating apparatus is formed in a high speed rotating bowl (outer rotating cylinder) 1 formed by connecting a conical cylinder 31 in front of a horizontally long straight trunk 30. The spiral blade 12 is installed in the inner cylinder (inner rotating cylinder) 11, and accommodates the screw conveyor 10 rotated with the relative speed difference with the bowl 1, and comes in the bowl 1 from the inner cylinder 11. Treatment liquids (a), etc. are supplied, and solid-liquid separation is performed by centrifugal force. Further, the dehydrated mass (b), which is a heavy component sedimented and separated by the centrifugal force in the bowl (1), is sequentially scraped and pushed toward the front end by the spiral blades (12), and the condensation and dehydration in the cone cylinder (31). It is discharged out of the apparatus from the sludge discharge port 7 of the front end, and the separation liquid c is discharged by overflowing from the discharge hole 32 formed in the rear end wall 3 of the bowl 1 on the opposite side. (Hereinafter, in the present specification, the direction in which the centrifugal force acts, that is, the direction in which the radius of the bowl increases, is referred to as a direction in which the radius decreases.)

This decanter type centrifugal separator is provided with a cone called a bezel in order to store the filtrate in the bowl 1 so that the filtrate is not discharged from the sludge discharge port 7 through which the mass is discharged. In order to increase the dehydration effect by raising the dehydration lump to a level higher than the level in the bowl, the conical cylinder 31 throttled with a small diameter to the level (water level) at least equal to the discharge hole 32 of the separation liquid is opened. It is characteristic that it is necessary.

These conventional centrifugal separators have been developed for the concentration or dehydration of crystals in liquid phases, but if they are to be used for the concentration or dehydration of a treated object, such as sludge, which has a different property from this, the precipitate of sludge is paste. It is phase and hydrophilic, and in order to increase the dehydration rate, it is necessary to apply a strong consolidation effect so as to throttle water. In the conventional gradient separator type centrifugal separator, when the treatment liquid a is supplied to the center portion of the bowl 1, the high centrifugal force field (about 2000 to 3000 G) is applied to the straight portion 30 of the bowl immediately after the supply. In the bowl cone portion 31 where the dehydrated mass (b) is discharged, the distance (diameter) from the center of rotation becomes short, so that the centrifugal force becomes weak and the water content becomes high. In fact, in the apparatus shown in FIG. 7, it is observed that the water content becomes the lowest in the d portion where the straight trunk and the cone are near the boundary. In addition, in order to discharge the sedimentation layer, it is necessary to raise the conical part against the strong centrifugal force, and even if it is transported by a screw conveyor, when the water content is low, a common turning occurs due to the frictional resistance, and the mass is stored. Without being discharged as it is, or vice versa, only agglomerates having a relatively high water content close to the center of rotation of the straight trunk portion 30 tend to be discharged.

In addition, since the dehydrated mass (b) passes through a large inclined cone cylinder for discharging beyond the water level in the bowl, slippage occurs at this portion and the discharge is worsened, and together with the separating liquid, the sludge separating liquid outlet 32 ), And the separation liquid is contaminated, resulting in defects. In addition, since the discharged dehydrated lump has a relatively high moisture content close to the center of rotation of the straight trunk portion 31, in order to lower the moisture content of the discharged dehydrated lump, the rotation speed of the bowl 1 is increased more than necessary. (2,000 ~ 3,000rpm) It is a fact that it is rotating. Therefore, it requires a lot of power.

In order to discharge paste-like deposits, which are difficult to transport on a screw conveyor such as sludge, in the state where the position of the outlet of the separation liquid is called a "negative dam" or "upstream", which is higher than the outlet of the precipitate. Rotation is done. In one such ambler type (US Pat. No. 3,172,851 and Japanese Patent Laid-Open No. Hei 6-190302), the sediment is discharged by using the head pressure of the liquid to be treated in the bowl.

However, since the liquid level in the bowl is high, the sediment remains at the beach even at the beach, and as a result, the water content increases due to the low head pressure due to the centrifugal force. As a result, the strong centrifugal force acts in the bowl. In any of the layers in the bowl, a strong pressing pressure is applied due to the centrifugal force acting on the liquid layer or the precipitate layer thereon. In this specification, this pressing pressure is called head pressure.]

In the Lee-type centrifugal separator, a partition plate with a small gap between the bowl wall and the partition plate is arranged near the boundary between the straight trunk and the cone, and only the lowest layer of the precipitation layer is taken out from the gap between the bowl wall and the partition plate. To get a low moisture content.

However, as described above, the paste-like precipitated layer having a low water content is difficult to be transported by a screw conveyor, and the available head is only the water level in the bowl, so that a lifting device (Japanese Laid-Open Patent Publication No. 4-59065) or the like can be used for discharging. It requires a special structure.

As one of this type, the treatment liquid is supplied from the rotating shaft of the bowl and the separating liquid and the sedimentation layer are discharged from the rotating shaft (Special Publication No. 63-31261). If the water content is low, the discharge may be difficult.

In the above various centrifugal separators, basically, the discharge of the sedimentation layer is at the same or higher position than the liquid level in the bowl, and the head pressure of the treatment liquid in the bowl is the head of the heavy sedimentation layer even if the discharge water pressure is used in the bowl. Smaller than the pressure, it is impossible in principle to discharge only the head pressure, and some discharge mechanism is required.

The present invention has been made to solve the problems in the above-described decanter type centrifugal separator, and in the conventional centrifugal separator, a centrifugal separator capable of directly discharging sludge from the d portion having the lowest water content. To get. As a result, the separation efficiency can be improved by promoting the separation, and the rotation speed of the bowl can be reduced, and the power can be reduced, and the device can be simplified and downsized because it has no conical portion.

In the centrifugal separator of the present invention, a centrifugal separator containing a screw conveyor rotated at a high speed in a bowl having a relative speed difference therebetween is provided with a discharge path for heavy components deposited in one wall of the bowl. An opening into the bowl of the discharge path is formed in the vicinity of the bowl inner circumferential wall. (In the present specification, the bowl means a portion where the treatment liquid is subjected to solid-liquid separation by the action of centrifugal force.) .

In this way, the discharge lump of the discharge path is discharged via the discharge path only from the portion of the sedimentation layer deposited at one end of the bowl, where the consolidation effect due to the head pressure of centrifugal force acting on the deposit is the highest.

If the treatment liquid is supplied into the bowl at the start of the centrifugal separator, it is not desirable to discharge the solids immediately from the outlet without concentrating and dehydrating the solids, so that the solids settle sufficiently (and thus, the degree of It is necessary to receive the action of centrifugal force for a certain time in the bowl. Therefore, it is advantageous to have a structure capable of maintaining the desired liquid level in the bowl at least in the initial stage of startup.

During operation, the outlet of the separation liquid may be referred to as a lower first class lower than the outlet of the dehydrated mass, or may be called a high upper first class. In the upper first class, the water surface in the bowl determined by the height of the outlet of the separation liquid is maintained by the sedimentation bed deposited on the discharge path side.

The discharge path acts as a throttle to limit the discharge of the dehydrated mass from the settling bed. In the centrifugal separator of the present invention, the dehydrated mass in the discharge path is mainly caused by the head pressure due to the centrifugal force of the sedimentation layer acting on the rear face, and furthermore, the conveyance force of the screw, and in some cases, the bowl. It is extruded by the supply pressure of the process liquid into it.

Since the discharge amount is determined by the discharge resistance received from the discharge path and the pressure for extruding the discharge path, when the thickness of the deposited layer of the heavy component deposited near the opening of the discharge path is small, the consolidation effect acting on the dehydrated mass is small. Is less. Thus, the thickness of the deposited layer near the opening of the discharge path is gradually increased by the deposition of the settled heavy components scraped off by the screw conveyor. However, as the thickness of the deposited layer increases, the extrusion force becomes stronger, thereby surpassing the discharge resistance to increase the discharge, and the thickness of the deposited heavy component deposited layer is kept constant by the balance of the deposited amount and the discharged amount.

In addition, since the specific gravity of the precipitation layer is larger than that of the treatment liquid, the head pressure available for discharge is larger than the head pressure of the treatment liquid used in the conventional apparatus. In the state of being stacked higher than this liquid level, the head pressure becomes very large, which facilitates the discharge of the dehydrated mass. In this case, the consolidation effect on the dehydrated mass by the sedimentation layer is maximized, and a low water content of the discharged solid content can be achieved.

1 is a side cross-sectional view showing the structure of one embodiment of a centrifugal separator of the present invention.

2 is a cross-sectional view along the line A-A in FIG.                 

3 is a cross-sectional view taken along line B-B in FIG.

4 is a partial cross-sectional view showing the structure of the discharge path in the centrifugal separator of the device of the present invention.

5 is a partial cross-sectional view showing another embodiment of the discharge path.

6 is a partial sectional view showing still another embodiment of the discharge path.

7 is a side cross-sectional view showing a conventional gradient separator type centrifugal separator.

8 is a partial cross-sectional view showing another embodiment of the bowl tip.

9 is a partial sectional view showing still another embodiment of the discharge path.

10 is a partial cross-sectional view showing the form of a valve provided at the discharge port at the end of the discharge path.

11 is a partial sectional view showing another embodiment of the valve.

EMBODIMENT OF THE INVENTION Hereinafter, the best form for implementing this invention is demonstrated with reference to drawings.

Figure 1 is a side cross-sectional view showing an embodiment of the present invention, Figure 2 is a cross-sectional view A-A of Figure 1, Figure 3 is a B-B cross-sectional view of Figure 1, Figure 4 is an enlarged view of the main portion.

1 to 4, 1 is a bowl (outer rotary cylinder) which rotates at a high speed, and forms a straight body of a horizontal cylinder, and is disposed at the center of the sludge discharge chamber wall 6 and the rear end wall 3, which are attached to the front end thereof. The hollow shafts 4 and 5 are formed to protrude, are supported by a bearing (not shown), and are rotated at a high speed by the drive device. Further, a plurality of sludge discharge ports 7 are formed in the circumferential wall of the sludge discharge chamber attached to the front end of the bowl 1 at intervals along the circumferential direction.

Although the sludge discharge chamber wall 6 and the sludge discharge port 7 are integrally formed with the bowl in the present embodiment, they are not the basic configuration of the centrifugal separator, but are formed separately from the bowl 1 as necessary. Therefore, proper design change is possible.

In addition, the outlet 8 of the separation liquid is formed in the rear end wall 3 of the bowl 1. The outlet 8 is formed, for example, with a plurality of fan-shaped ones spaced apart in the circumferential direction, or as shown in FIG.

10 is a screw conveyor accommodated in the bowl 1, and the spiral wing 12 is wound around the outer periphery of the horizontal cylindrical rotating body 11, The both ends are the hollow shafts 4 and 5 of the bowl 1, respectively. The rotating shaft 13 supported by the protrusion in the bowl of the bowl and inserted into the hollow shaft 4 is rotated with the required speed difference from the bowl 1. In the rotating body 11, a supply chamber 14 of the processing liquid a is provided, and a circumferential wall is provided to communicate with the annular space 17 between the bowl 1 and the rotating body 11. While the sphere 15 is open, the supply pipe 16 for the processing liquid inserted through the rear hollow shaft 5 of the bowl 1 is opened in the supply chamber 14.

A wall 2 is provided at the front end of the annular space 17 of the bowl 1, and a discharge path 20 of the dehydrated mass b is provided in the wall 2. Referring to FIGS. 1 and 4, the opening 20a into the bowl of the discharge path 20 is formed in contact with the inner surface of the circumferential wall of the bowl 1, and in the present embodiment, as the discharge port outside the bowl, The openings 20b to be formed have a height in the radial direction. Therefore, the deposits permeable to the discharge path by the openings 20a are limited to only the lowermost part of the deposit. On the other hand, the opening portion 20b is supplied at such a level that the processing liquid is not supplied to the opening portion 20b at the beginning of operation, so that the initial height of the liquid level in the bowl is determined.

If the opening portion 20b is too high, the centrifugal force acting on the dewatered mass of the discharge path 20 cancels the pressing pressure applied to the sedimentation layer in the bowl, so that the discharge force of the dehydrated mass is reduced. Low is desired.

On the other hand, the discharge port 8 of the separating liquid determines the liquid level of the annular space 17 during operation, and when the position of the discharge port 8 is lower than the opening portion 20b, the discharge port 8 is operated in the so-called "lower first-class" state. When it is high, it becomes operation in the "upstream first class" state. In the case of the operation in the upper first-class state, the discharge of the processing liquid from the discharge path 20 is prevented by the deposition layer deposited near the opening 20a.

In the extreme case, the separation liquid can be discharged from the shaft center.

In the above apparatus, the treatment liquid a to be dewatered enters the supply chamber 14 from the supply pipe 16 as shown by an arrow, is supplied from the supply port 15 into the annular space 17, and the bowl 1. And by the centrifugal force of the rotation of the screw conveyor 10 is to be conveyed toward the front end by the spiral wing 12. The separating liquid (c), which is the separated liquid powder, is discharged out of the apparatus from the outlet 8 of the rear end wall.

On the other hand, the sedimentation layer is scraped out in the direction of the front end of the bowl 1 by the spiral blades 12, and further subjected to a separation action by centrifugal force, and the separation of the residual liquid fraction proceeds, and this separation liquid (c) is also discharged. It is discharged from (8).

On the other hand, the sedimentation layer conveyed in front of the bowl 1 deposits by the difference with the discharge | emission from the discharge path 20 at the front end of the annular space 17. If the deposited heavy component is, for example, sand, the specific gravity is about 2.5 to 3, and is significantly heavier than that of water. Therefore, the head pressure due to the centrifugal force acting on the deposited layer is more than twice that of water. In addition, if the height of the liquid level determined by the separating liquid outlet 8 is lower than the rotary body 11, and there is a space left in between, the sedimentation layer is piled up beyond the liquid level, the size of the specific gravity and the accumulation By the height of, the large consolidation effect on the sedimentary layer in which the large centrifugal head pressure acts in the vicinity of the volleyball 20a of the discharge path occurs, and the centrifugal head pressure and the conveyance force of the screw cause the extrusion action to the discharge path.

The centrifugal separator of the present invention is not limited to the above structure, and various design changes can be made within the scope of the present invention.

5 shows another embodiment of the discharge path 20. In this embodiment, the discharge path 20 does not form a straight line inclined at its end as in the previous embodiment, but is substantially parallel to the wall 2 between the openings 20a and 20b. It includes.

The discharge path having such a shape can have a difference in length (that is, discharge resistance) and height required between the openings 20a and 20b even when the thickness of the wall 2 is relatively thin.

The front end wall 2 of the said annular space 17 can be comprised by two members arrange | positioned at small intervals so that the said discharge path 20 may be formed. That is, the member 21 is formed to protrude in the direction of the rotation axis from the vicinity of the inner wall of the bowl, and is formed to protrude to the rotating body 11, and extends substantially at regular intervals from the member 21, the discharge path between the It is possible to comprise the member 22 to form.

Alternatively, as shown in FIG. 6, the members forming these discharge paths 20 may be separated from the bowl 1 and the rotating body 11, and may be fixed by bolts or other means. At this time, by fitting the spacers 23 together and appropriately selecting the thickness of the spacers, it is possible to modify the size of the discharge path 20 formed therebetween. In FIG. 6, the upper half shows a case where the discharge path is thin and the lower half shows a large case.

In this way, the discharge resistance can be adjusted by changing the size of the discharge path, but the height from the inner wall of the bowl at the front end of the member 22 is constant, and the discharged portion in the deposited layer is invariable.

It goes without saying that the distance adjustment of the members 21 and 22 may be made by moving each member with a screw or the like without using a spacer. By adjusting the discharge resistance as described above, the discharge and the moisture content can be adjusted.

In addition, it is also possible to change the part discharged | emitted in a laminated layer by changing the height of the member 22 as needed.                 

In the above embodiment, the wall 2 at the front end of the bowl in which the discharge path 20 of the dehydrated mass is provided is formed as an opposing portion between the bowl circumferential wall and the screw conveyor 10, but in the embodiment shown in FIG. In this case, the wall 32 in front of the bowl is a member that rotates integrally with the bowl 1, and the screw conveyor 30 is enclosed in the bowl 1. In the case of having such a structure, in order to prevent intrusion of the processing liquid into the bearing 33, it must be sealed with the high pressure packing 34.

In addition, in the said embodiment, in the beginning of operation, the opening 20b out of a bowl was set higher than the opening 20a in a bowl so that a process liquid may not be discharged from the discharge path 20 as it is. . However, at the beginning of operation, as shown in FIG. 9, the opening 20b is set at the same height as the opening 20a or lower than the opening 20a by a method such as closing the discharge path with the valve 35. It is possible to do this, and it is possible to make discharge of a dehydrated mass easier by this.

The valve 35 must be opened starting with the increase in the head pressure of the sedimentation layer without being opened by the centrifugal force due to the bowl operation. 10 and 11 show needle valves as an example of such a valve.

8 to 11, the discharge paths 20 are formed as a plurality of discharge holes arranged along the circumferential direction of the bowl wall.

As described above, the centrifugal dewatering device of the present invention directly discharges only the portion of the sedimentation layer in the bowl which has the highest consolidation action, based on a technical concept different from that in the conventional centrifugal separator. As a result, the moisture content of the dehydrated mass can be lowered to an extent that no example can be found in a conventional centrifuge.

In addition, although it is common for the sediment layer having a low water content to be difficult to discharge, in the centrifugal separator of the present invention, a special discharge means is utilized by using the high head pressure generated by forming a high sediment layer by the discharge resistance of the discharge path. It is possible to discharge without installing.

For this reason, it is possible to obtain a high dehydration rate and a high separation efficiency while being a relatively small device with a relatively simple configuration.

Claims (9)

It has a cylindrical bowl rotating in one direction, and a screw conveyor rotating coaxially with the bowl in the bowl and having the difference in rotational speed in the same direction. In the centrifugal separator for sedimentation and sedimentation, this is integrated on one side of the bowl by a screw conveyor, and the heavy component and the separation liquid are separated and discharged. The bowl forms a straight body of a horizontal cylinder, and installs a discharge path of heavy components deposited in one wall of the bowl, and an opening into the bowl of the discharge path is provided in contact with an inner surface of the main wall of the bowl. Is a throttle passage limiting the discharge amount, and the discharge resistance of the throttle passage forms a deposited layer of a heavy component in the maximum consolidation state near the opening, and the centrifugal head pressure acting on the deposit is formed. And by the conveying force of the screw conveyor, the centrifugal separator characterized in that directly discharging only the maximum consolidation state portion. delete The centrifugal separator according to claim 1, wherein the outlet of the bowl of heavy components deposited from the discharge path is formed at a radius smaller than the bowl radius. The centrifugal separator according to claim 1, further comprising: a member extending in the rotational axis direction from the vicinity of the inner wall of the bowl, and a member extending at a predetermined distance from the member and forming a discharge path between the member. 5. The centrifugal separator according to claim 4, wherein the member extending in the rotational axis direction from the vicinity of the inner wall of the bowl is a member having a conical inner surface, and the member extending at regular intervals from the member is a member having a conical outer surface. The centrifugal separator according to claim 4, wherein the member extending in the rotational axis direction from the vicinity of the inner wall of the bowl and the member extending at regular intervals from the member are disposed in the bowl so as to be replaceable. 7. The centrifugal separator according to claim 6, wherein the member extending in the rotation axis direction from the vicinity of the inner wall of the bowl is a member having a conical inner surface, and the member extending at regular intervals from the member is a member having a conical outer surface. . The centrifugal separator according to claim 4, wherein at least one of the members extending in the rotational axis direction from the vicinity of the inner wall of the bowl and the members extending at regular intervals from the member are movable in the bowl axial direction. 9. The centrifugal separator according to claim 8, wherein the member extending in the rotational axis direction from the vicinity of the inner wall of the bowl is a member having a conical inner surface, and the member extending at regular intervals from the member is a member having a conical outer surface. .

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